Re: [CAD_CAM_EDM_DRO] Power Supply and Capacitor Questions Help!!

R Rogers wrote:

>Hi Jon,
>
> Thank you for taking the time to reply. Your posts are always informative. I rechecked those two taps and they are actually 33 volts and 12 volts. I wired them in parallel and read 45 volts from them combined. You mention they may not be isolated. How would I know if they are or not? ohm meter and check for continuity from one side to the other?
>

Yes, exactly.

> I hooked one leg from each tap and checked the voltage as I just mentioned and I left the powers supply on for 2 hours and it got rather warm with no load on it. Is this normal? It was touchable but, rather warm. What Capacitance do you recommend? I'm running three DC brush servo motors at 13.7 amps continuous on Gecko 320's.
>

What voltage are the motors? Do you have a Kv constant for the motor?
Making a number of assumptions, here, your worst-case current draw would
be 13.7 A x 3 = 41 Amps. At 41 A, a 45,000 uF cap bank would drain at the
rate of 911 V/Sec, or .911 V/ mSec. Assuming 8.7 mS between power line
half cycles, that would be a droop of about 8 V. Since this is an absolute
worst-case scenario, meaning the motors were all delivering rated peak
torque at max speed (where the Gecko's output voltage was equal to the
input voltage), this can't be sustained for very long. I think you need all
3, unless you can show that the motors will never deliver peak torque at
a speed where the full ~60 V will also be delivered to the motors at the
same time.

Jon